For small [tex]V_0[/tex] this potential can be considered as a small perturbation of a “box” with a straight bottom, for which we have already solved the Schrodinger equation. What is the perturbation potential [tex]\Delta[/tex]V (x)?

c)

Calculate the energy shift due to the sagging for the particle in the nth stationary state to first order in the perturbation.

2. Relevant equations

3. The attempt at a solution

I have completed the first section with a graph as attached. I am not sure on the second part. I know for a inharmonic oscillator,